Mercurial > hg > octave-nkf > gnulib-hg
changeset 11883:729b89da65db
Fix getdtablesize() on mingw.
author | Bruno Haible <bruno@clisp.org> |
---|---|
date | Sun, 23 Aug 2009 21:55:26 +0200 |
parents | 52791eb62094 |
children | 0c06eef5cb3b |
files | ChangeLog lib/getdtablesize.c lib/unistd.in.h |
diffstat | 3 files changed, 40 insertions(+), 3 deletions(-) [+] |
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--- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2009-08-23 Bruno Haible <bruno@clisp.org> + + Fix getdtablesize() on mingw. + * lib/getdtablesize.c (getdtablesize): Implement differently. + * lib/unistd.in.h (getdtablesize): Improve comment. + 2009-08-23 Bruno Haible <bruno@clisp.org> New module 'mkostemp'.
--- a/lib/getdtablesize.c +++ b/lib/getdtablesize.c @@ -1,5 +1,5 @@ /* getdtablesize() function for platforms that don't have it. - Copyright (C) 2008 Free Software Foundation, Inc. + Copyright (C) 2008-2009 Free Software Foundation, Inc. Written by Bruno Haible <bruno@clisp.org>, 2008. This program is free software: you can redistribute it and/or modify @@ -24,10 +24,40 @@ #include <stdio.h> +/* Cache for the previous getdtablesize () result. */ +static int dtablesize; + int getdtablesize (void) { - return _getmaxstdio (); + if (dtablesize == 0) + { + /* We are looking for the number N such that the valid file descriptors + are 0..N-1. It can be obtained through a loop as follows: + { + int fd; + for (fd = 3; fd < 65536; fd++) + if (dup2 (0, fd) == -1) + break; + return fd; + } + On Windows XP, the result is 2048. + The drawback of this loop is that it allocates memory for a libc + internal array that is never freed. + + The number N can also be obtained as the upper bound for + _getmaxstdio (). _getmaxstdio () returns the maximum number of open + FILE objects. The sanity check in _setmaxstdio reveals the maximum + number of file descriptors. This too allocates memory, but it is + freed when we call _setmaxstdio with the original value. */ + int orig_max_stdio = _getmaxstdio (); + unsigned int bound; + for (bound = 0x10000; _setmaxstdio (bound) < 0; bound = bound / 2) + ; + _setmaxstdio (orig_max_stdio); + dtablesize = bound; + } + return dtablesize; } #endif
--- a/lib/unistd.in.h +++ b/lib/unistd.in.h @@ -328,7 +328,8 @@ #if @GNULIB_GETDTABLESIZE@ # if !@HAVE_GETDTABLESIZE@ -/* Return the maximum number of file descriptors in the current process. */ +/* Return the maximum number of file descriptors in the current process. + In POSIX, this is same as sysconf (_SC_OPEN_MAX). */ extern int getdtablesize (void); # endif #elif defined GNULIB_POSIXCHECK